The present invention provides a system for enabling the sensing of changes in pressure in response to uterine muscle tone changes relating to contractions, and for enabling the evaluation of contractions based thereon. The system enables a portion thereof to effectively and efficiently project at least partially below the non-compressed abdominal surface, and provides electrical isolation of the system elements. It enables ease of use and enhanced patient comfort. It also enables maximized sensitivity and minimized system loading retention pressure.
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1. A system for sensing the frequency and duration of uterine contractions of a patient during labor and estimating the relative intensity thereof, able to sense changes in pressure in response to uterine muscle tone changes relating to contractions, and to enable a fetal monitor to be connected thereto for evaluation of contractions, comprising:
a supporting element, including a facing side able to face an exterior abdominal wall proximate a uterine muscle of a patient and be positionable thereagainst, and able to support a force collector, and a pressure sensor positioned adjacent to the force collector, for supporting the force collector and the pressure sensor such that the force collector and the pressure sensor project therefrom, and shaped such that the projecting force collector and adjacent pressure sensor project into the abdominal wall to reside at least partially below the non-compressed surface of the abdomen to sense changes in pressure in response to uterine muscle tone changes relating to contractions, upon postioning the facing side of the supporting element so as to face the exterior abdominal wall proximate the uterine muscle of the patient;
a force collector, for collecting force generated in response to uterine muscle tone changes relating to contractions, positioned on the facing side of the supporting element and shaped so as to project therefrom so as to project into the abdominal wall to reside at least partially below the non-compressed surface of the abdomen upon positioning the facing side of the supporting element on the exterior abdominal wall proximate the uterine muscle of the patient; and
a pressure sensor, for sensing changes in pressure in the force collector responsive to uterine muscle tone changes, positioned adjacent to the force collector.
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This application is a division of application Ser. No. 11/123,862 filed May 6, 2005 now U.S. Pat. No. 7,862,521, which was a continuation-in-part of a co-pending application Ser. No. 10/113,890 filed on Mar. 27, 2002.
1. Field of the Invention
This invention is generally related to devices for sensing uterine contractions during labor, and more particularly, to a system and method for sensing the frequency and duration of contractions, and for estimating the relative intensity thereof.
2. General Background and State of the Art
During a contraction, the muscle tone of the uterus increases. This increase in muscle tone applies pressure to the abdomen. The abdomen hardens and the shape changes due in part to the muscles surrounding the anterior ligament of the uterus pulling the abdomen forward.
It is known to provide systems for estimating the force of uterine contractions during labor, generally known as tocodynamometers, which sense, in relative terms, the increase and decrease in abdominal pressure relating to uterine contractions, and enable evaluation thereof. Such systems have typically included a cantilevered beam as a sensor, and a button as a force collector, which is connected to the sensor by a link pin. The output from the system is sent to a. fetal monitor, which displays the relative pressure in the form of a digital reading and strip chart recording. The clinician, in reviewing the chart recording, can observe the progress of labor in terms of contraction frequency and duration, and can obtain a rough indication of the relative intensity of the contractions.
However, such systems are relatively large and bulky, require relatively large devices to hold them in place, and are expensive. Further, they are relatively difficult to use, require relativly high belt tension which is uncomfortable, and tend to migrate and require repositioning.
It would therefore be desirable to provide a sensing system which would sense the frequency and duration of uterine contractions during labor, and estimate the relative intensity thereof, in a manner which would maximize the sensitivity of the system and enhance ease of use and patient comfort. It would further be desirable to enable unique leveraging thereof, for loading onto the abdomen with the exertion of substantially minimal retention pressure. It would still further be desirable to enable support of the system so as to project into the abdomen wall to efficiently reside below the non-compressed abdominal surface. Moreover, it would be desirable to provide electrical isolation of the patient, to prevent the flow of current thereto
Therefore, there has been identified a continuing need to provide a sensing system which will effectively sense uterine contraction frequency and duration during labor, for enabling efficient estimation of the relative intensity thereof.
Briefly, and in general terms, the present invention, in a preferred embodiment, by way of example, is directed to a system for sensing the frequency and duration, of uterine contractions during labor and estimating the relative intensity thereof. The system is able to sense changes in pressure in response to uterine muscle tone changes relating to contractions, and to enable a fetal monitor to be connected thereto for evaluation of contractions. The system includes a pressure sensor, for sensing changes in pressure responsive to uterine muscle tone changes, positionable against the exterior abdominal wall proximate the uterine muscle, connectable to a fetal monitor for evaluation of contractions during labor, and supportable so as to project into the abdominal wall to reside at least partially below the noncompressed surface of the abdomen. The system also includes a supporting element, for supporting the pressure sensor such that the pressure sensor projects into the abdominal wall to reside at least partially below the non-compressed surface of the abdomen.
In accordance with another aspect of the invention, the supporting element may include extending portions which extend from the opposed sides thereof, which include attachment portions and attachment points at the opposed ends thereof, for enabling a securing element to be connected to the attachment portions and attachment points in the opposed ends of the extending portions, to secure the system about the abdomen. The system further includes a force collector, which includes edges thereof. The leveraging provided by the extending portions including the attachment portions, and a leveraging ratio of the distance from the attachment points through the force collector edges, is sufficiently flexible to enable deflection with the tension exerted by the securing element thereon, so that the supporting element conforms to the natural curvature of the abdomen.
In another aspect of the invention, the force collector is secured to the pressure sensor, and a protective cover extends over the force collector for protectively covering the force collector. The protective cover may have a vent hole therein, for enabling the venting of trapped air therethrough, and for preventing zero shifts which might occur due to thermal effects. The protective cover enables the force collector to slide over the patient's skin, and prevents sticking upon repositioning thereof, which might otherwise cause negative pressure readings when the pressure cover is unloaded and returns to its natural state.
In still another aspect of the invention, the force collector includes an outer section and an inner section, and the coefficient of thermal expansion of the outer section of the force collector is substantially similar to the coefficient of thermal expansion of the inner section of the force collector, to prevent a zero shift in the pressure reading as the system warms on the patient's skin.
In a further aspect of the invention, the force collector further includes an outer portion of the outer section, and an inner portion of the outer section, and the average thickness of the outer portion of the outer section of the force collector is less than the average thickness of the inner portion of the outer section of the force collector, to overcome slight differences in coefficients of thermal expansion of the outer portion and the inner portion of the outer section of the force collector. The outer portion of the outer section is retained firmly against a non-moving surface, keeping the thickness of the outer portion down in this area, and allowing the outer section to move more freely over the inner portion of the outer section, so as to negate at least a portion of any expansion differences.
In still further aspects of the invention, the supporting member includes a plurality of contact pads, and the system further includes a cable for connecting to a fetal monitor at one end thereof, a plurality of connectors extending from the opposite end of the cable and secured to the plurality of contact pads, and a plurality of wires extending from the sensing member to the contact pads. The plurality of connectors may each comprise solid unstranded telephone cable, and the cable which is connectable to the fetal monitor may include an extended venting lumen for enabling venting therethrough, and for enabling underwater use thereof. Solid wire makes it less labor intensive to solder to the contact pads, as there is no twisting and trimming of strands.
In accordance with other aspects of the invention, the plurality of connectors in the cable which is connectable to the fetal monitor are able to be soldered directly to the contact pads, for providing a secure connection thereof. In still further aspects of the invention, the programming element comprises a user interface module, includes a processor, and is programmable for a time within the period of the minimum time required to complete a flush of the toilet to the maximum time required to drain all of the water from a toilet tank. It is positionable at a user-accessible location.
In other aspects of the invention, the opposed ends of the extending portions of the supporting element include slots and posts, and the securing element includes opposed ends and has buttonholes. The opposed ends of the securing element are able to extend directly over the post, and each of the buttonholes is able to stretch over and interlock with the post to engage therewith for securing the system about the abdomen.
In another aspect of the invention, the opposed ends of the extending portions of the supporting element include slots, and the securing element includes opposed ends, each of which includes interengageable elements. The opposed ends of the securing element are able to extend through the slots in the opposed ends of the extending portions and fold thereover, and the interengageable elements are able to interengage for securing thereof.
In still other aspects of the invention, the system further includes a cover, for covering the supporting member, the sensing member, and a portion of the cable which is connectable to the fetal monitor. The cover includes a pair of posts, one on each of the opposed ends thereof, the securing element includes opposed ends, and has buttonholes, and each of the buttonholes in the securing element is able to stretch over and interlock with one of the posts to engage therewith for securing the system about the abdomen.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.
Referring to the drawings, in which like reference numerals refer to like or corresponding parts, the system according to the invention senses the frequency and duration of uterine contractions during labor and estimates the relative intensity thereof. The system is able to sense changes in pressure in response to uterine muscle tone changes relating to contractions, and to enable a fetal monitor to be connected thereto for evaluation of contractions.
The pressure sensor 12 is generally small and lightweight, and the supporting element 14 is generally low profile and lightweight. The pressure sensor 12 is further able to be actuated by an excitation voltage from a fetal monitor, and to send a signal voltage back to the fetal monitor responsive to changes in pressure. The pressure sensor 12 may comprise a piezo-resistive pressure sensor. It includes a supporting member 20, and a sensing member 22 for sensing changes in pressure responsive to uterine muscle changes relating to contractions, and for enabling a fetal monitor to be connected thereto. The sensing member 22 is supported in the supporting member 20.
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The sensing member 22 is supported in the supporting member 20 such that the sensing member 22 is able to project into the abdominal wall to reside at least partially below the non-compressed surface of the abdomen. The sensing member 22 comprises the active area of the pressure sensor 1.2. It includes resistors, which may comprise for example thin film resistors deposited thereon, which resistors are able to change the resistance with. changes in applied pressure. The resistors in the sensing member 22 may comprise a balanced resistor network, which may comprise a silicon semiconductor Wheatstone bridge. The sensing member 22 and the supporting member 20 for example may comprise a pressure transducer. Alternatively for example the sensing member 22 and a supporting portion of the supporting element 20 may comprise a pressure transducer, or for example the sensing member 22 and a supporting part of the supporting element 20 may comprise a pressure transducer. The ceramic chip substrate 32 of the supporting member 20 may include compensating resistors therein, for providing compensation for the resistors in the sensing member 22.
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The force collector 16 is generally in the shape of a nipple, and may be comprised of a generally soft and compliant material. The generally compliant material of which the force collector 16 is comprised for example may be a generally compliant polymer material, a generally compliant monomer material, or another generally compliant material such as latex. The force collector 16 may alternatively for example be comprised of a generally noncompliant material which includes compliant material therein, such as an oil. The generally compliant material and the generally non-compliant material may comprise a generally soft low durometer material or a generally non-low durometer non-compliant material. The system 10 may include a protective cover 52, which extends over the force collector 16 to provide additional protection for the generally low durometer embodiment of the force collector 16. The protective cover 52 may be thin, may be comprised of polyethylene, and may have a vent hole 54 therein, for enabling the venting of trapped air therethrough. The protective cover 52 also enables the force collector 16 to slide over the patient's skin, and prevents the force collector 16 from sticking to the patient's skin, when the clinician wishes to reposition the system 10. The vent hole 54 prevents the air from expanding as it warms up on the patient's abdomen, which may otherwise cause a zero shift in the pressure reading. The protective cover 52 is also able to prevent sticking of the force collector 16, which might otherwise pull on the force collector 16 causing negative pressure readings when the protective cover 16 is unloaded and returns to its natural state.
An outer section-inner section ratio comprises the ratio of the linear width of the force collector outer section 46 to the linear width of the force collector inner section 48. The width of the linear width of the outer section 46 of the force collector 16 comprises the linear widest width thereof. The ratio for example is no greater than about three and one-half to one, and may be about two and one-half to one. An interface-inner section ratio comprises the ratio of the cross-sectional area of the width of the force collector interface 50 to the cross-sectional area of the width of the force collector outer section 46. The interface-inner section ratio of the interface 50 of the force collector 16 to the outer section 46 of the force collector 16 is substantially minimal. The interface-inner section ratio may comprise the ratio of the cross-sectional area of the width of the interface 50 to the cross-sectional area of the width of the inner section 48. The cross-sectional area of the width of the force collector 16 comprises the cross-sectional area of the widest width thereof. The ratio for example is no greater than about eight to one, and may be about four to one.
The coefficient of thermal expansion of the solid non-fluid outer section 46 of the force collector 16 is substantially similar to the coefficient of thermal expansion of the solid non- fluid inner section 48 of the force collector 16. If there is a difference in the coefficient of thermal expansion between the outer section 46 and the inner section 48 of the force collector 16, a zero shift in the pressure reading may result as the system 10 warms on the patient's skin. The average thickness of an outer portion 56 of the outer section 46 of the force collector 16 is less than the average thickness of an inner portion 58 of the outer section 46 of the force collector 16, to overcome slight differences in coefficients of thermal expansion of the outer portion 56 and the inner portion 58 of the outer section 46 of the force collector 16. The outer portion 56 of the outer section 46 is retained firmly against a nonmoving surface, thereby keeping the thickness of the outer section. 46 down in this area, and allowing the outer portion 56 of the outer section 46 to move more freely over the inner portion of the outer section 46, so as to negate at least a portion of any expansion differences.
The pressure sensor 1.2 is able to be formed such that ratios of the pressure sensor 12 relative to the force collector 16 are substantially minimal so as to maximize the sensitivity of the system 10. An inner section-sensing member ratio of the inner section 48 of the force collector 16 to the sensing member 22 of the pressure sensor 12 is substantially minimal. The inner section-sensing member ratio comprises the ratio of the area of the width of the force collector inner section 48 to the width of the sensing member 22. The width of the force collector inner section 48 and the width of the sensing member 22 comprises the width in any direction thereof. The ratio for example is no greater than about three and one-half to one, and may be about two and one half to one. Alternatively, the inner section- sensing member ratio comprises the ratio of the area of the force collector inner section 48 to the area of the sensing member 22. The ratio for example is no greater than about eight to one, and may be about five to one.
The securing element 18 for example comprises a belt, which is comprised of generally elastic material. The generally elastic material may for example comprise an elastic nylon material, or an elastic polyester material. The supporting element 14 also leverages the pressure sensor 12, so as to enable the securing element 18 to load the pressure sensor 12 onto the abdomen, with substantially minimal retention pressure exerted by the securing element 18 on the pressure sensor 12. Further, the supporting element 14 is comprised of a flexible material or a non-flexible material, such that, in conjunction with the securing element 18, the flexible material or the non-flexible material maintains a load on the pressure sensor 12 during abdominal changes in response to contractions. The flexible material of which the supporting element 14 may be comprised is preferably a flexible plastic material, which flexible plastic material may constitute for example a thermoplastic such as polycarbonate.
In the embodiment as seen in
The supporting element 14 may include an inhibiting portion 74, comprising a ridge area 76, as seen in
In the embodiment shown in
The
The supporting element 14 is generally low profile and lightweight. It includes a housing 92 which includes a mounting portion 94 for mounting the pressure sensor 12 therein, is generally semi-spherical in shape, generally in the form of a dome, and includes a recess 96 in the form of a well therein. The pressure sensor 12 is able to project from and be moveable in the recess 96 of the supporting element 14. The housing 92 further includes a generally rectangular-shaped back portion 98 from which the mounting portion 94 projects. The supporting element 14 may be is comprised of a flexible or non-flexible material, such that the flexible or non-flexible material maintains a load on the pressure sensor 12 during abdominal changes relating to contractions. The flexible material may comprise a flexible plastic material.
While the particular sensing system as shown and disclosed in detail herein is fully capable of obtaining the objects and providing the advantages previously stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention, and that no limitations are intended to the details of construction or design shown herein other than as described in the appended claims.
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